Apparatus for coating metal sheets



Feb. 24, 1931.

E. w. SHHNN ET AL APPARATUS FOR COATING METAL SHEETS Filed July 20. 1928 INVENTORS TPatented Feb. 24, 1931 UNITED STATES PATENT oFFIce EDMUND W. SHINN AND ROBERT E. SCOTT, F CUMBERLAND, MARYLAND APPARATUS FOR COATING METAL sfimrs Application filed July 20,

- Our invention relates to a method of and apparatus for coating metal sheets and is hereinafter described as employed more particularly in the manufacture of tin plate, but

6 it will be understood that the invention is susceptible of use also in various other relations.

In the manufacture of tin plate that is to be made into articles which are used but 10 once, as for instance to serve as containers for canned foods, it is desirable, as a matter of economy, to have the tin coating as thin as possible. Various means have been employed for removing surplus tin from the coated sheets as they emerge from the bath of molten tin, but the older methods are unsatisfactory in various respects. For instance, where the surplus tin is removed by passing the sheet between rolls that exert a squeezing action on the sheets, impurities which are present in the tin adhere to the rolls thus making roughened raised spots that result in marring the sheets and also prevent close contact of the roll surfaces with the sides of the sheets. Again, the rolls have usually been made of materiahwhich, assisted by the fluxing action of palm oil or chloride of zinc, become coated with the metal from the-pot.

One object of our inventionis to provide a means and a method whereby particles which adhere to the" tinning rolls may be more efiectively removed than by the use of prior methods.

Another object of our invention is to provide tinning rolls of such character that there will be less tendency of palm oil or chloride of zinc fluxing the surface of the roll, thereby rendering the rolls less liable to be thereto of particles of impurities.

Still another object of our invention is to simplify and improve generally the art of coating sheets. I I

One form of apparatus by which our invention may be practised is shown in the accompanying drawing, ,wherein Figure 1 is a cross sectional viewof an installation for coating sheets; Fig. 2 is a view, on an enlarged scale, of one of the Stripping elements of Fig. 1,

come coated with metal or for the adherence 1928. Serial 1%. 294,099.

but showing the same slightly modified, and Fig. 3 is a plan view of one of the stripping elements.

The apparatus may be mounted upon a ;tin pot 4 of any well-known type which contains the molten tin through which the sheets are passed. Within the pot 4, we provide a pair of feed rollers 5 and a guide plate 6, the sheets being fed between the rollers 5 which are rotated in any well known manner and caused to advance along the guide plate 6 to the upper feed rollers.

The upper feed rollers are arranged in pairs 7, 8 and 9, that are rotated in a suitable manner to advance the sheets upwardly and to simultaneously squeeze surplus coating material, such as molten tin therefrom. In conjunction with each feeding and squeezing roller, there is a swinging yoke composed of a bracket 10 which is attached to an angle bar 11 by means of bolts 12. A stripper'knife .13 is also supported in position upon each of the yokes 10 by the bolts 12 and. by the angle bar 11. These knives 13 each have sharp edges that bear against the respective rollers for the purpose of stripping adhering material therefrom. The plates are of spring- -like material and are pointed against the direction of rotation of the rollers so that not only will they more effectively remove waste material therefrom, but their frictional contact with the rollers will cause the knife edge 4 to be maintained in a sharpened condition.

If desired, the knives 13 can be backed by additional spring plates or laminations, such as 14 (Fig. 2) to cause them to bear more firmly against the rolls. In order to more effectively clean the rolls and to serve as stop members for accurately maintaining the knives 13in proper position with respect to the rolls, we provide brushes 15 of asbestos or other suitable material. Other material than asbestos or the like may be substituted for the members 15, if it is desired merely to have such members serve as stop or positioning members for the stripping plates. 7 .7

The extremities of ,-the yokes or brackets 10 are recessed so that they may engage ins 16 which project from the end frames 0 the machine. The brackets 10 and the cleaning elements are held in seated positionagainst the pins 16 and the feed rolls respectively, by means of hook bolts 17, whose lower ends engage loops 18 which are riveted to the yokes. Nuts 19 have threaded engagement with the upper ends of the bolts17 and abut against springs 20 whose lower ends seat upon plates or angles 21. It will be understood that when the nuts 19 are tightened, the bolts 17 will be drawn upwardly andthe knives and brushes will be held in contact with the feed rolls. As the knives and brushes wear down, the necessary adjustment of the nuts 19 can, of course, readily be made. Such adjustments will not have to continually be made, for the reasons that the springs 20 will automatically take up the bolts to compensate for wear, and the inherent flexibility of the knives 13, will also automatically take care of ordinary wear thereof to some extent.

' It will be seen that the working positions of the knives 13. are at angles relative to the diametral lines of their respective rollers, and that the material is so deflected by the knives from the rollers that it will not again come in contact with the rolls.

As a means of reducing the tendency for material to adhere to the rolls, we may make the rolls of chrome, or other alloy, or stainless steel, or other suitable metal, or subject them to a sherardizing, parkerizing or similar process to prevent the fluxing action of palm oil, chloride of zinc, etc. and for the purpose of rendering the rolls less susceptible to becoming coated with the metal from the pot. The knives may or may not be employed in connection with rolls of this character, as desired.

In modern practice, the rolls employed are quite hard, being usually from about 40 to 55 sclerescope. lVhile the coating material will not so readily adhere to these rolls as to the softer rolls of the older practice, the impurities will adhere thereto much more firmly and cannot be removed therefrom by brushes as well as they can be removed from the softer rolls. This difiiculty of removing impurities from the harder rolls may be overcome by the use of our stripper knives.

While asbestos brushes have heretofore been employed for the purpose, it has been necessary to cause them to bear against the rolls with great force, With the result that they wear down rapidly and operations have to be suspended until they can be changed. By our arrangement, either with or without the brushes, the apparatus can be employed for many weeks continuously without the necessity of ceasing operations in order to permit of the renewal of brushes or stripper knives. Furthermore, as above stated, we can prevent the impurities from adhering to the rolls, thus making it possible to apply heretofore, and also rendering it unnecessary to remove the rolls so frequently for the purpose of turning or grinding them down.

Not only does the arrangement of knives of bladelike form with their edges pointing oppositely to the direction of rotation of rolls and the employment of rolls not susceptible of becoming coated with tin, as heretofore pointed out, result in keeping the rolls smooth and clear of tin coating, with consequent uniformity in thickness of coating material on the sheets, but keeping the rolls clear of tin coating results in a saving of tin, since it has been found that the amount of coating remaining on the sheets after passing largely in direct proportion to the thickness of coating on the rolls.

We claim as our invention 1. The combination with a coating machine having squeezing rolls throu h which coated sheets are advanced, of knives bearing against the rolls, an adjustable support for the knives, and means for positioning said support for varying the position of the knives with respect to the rolls, the knives being of blade-like form, with their edges pointed against the direction of rotation of the rolls.

2. The combination with a coatin machine having squeezing rolls through which .coated sheets are advanced, of knives bearing against the rolls, an adjustable support for the 

